I. Field of the Present Invention
The present invention relates generally to fluid activated expansion devices, and more particularly, to an expansion motor having a fitting enclosing one end of an inflatable tube and a fitting with a fluid coupling at the other end of the tube.
II. Description of the Prior Art
Inflatable hose type power units are previously known and generally comprise fittings at the ends of the hose for sealing the ends. It is also known that at least one of the hose end fittings can be specially constructed to include ports so that a pressurized fluid can be introduced into and exhausted from the hose interior.
Some previously known power units of this type are disclosed in U.S. Pat. No. 3,016,884, U.S. Pat. No. 2,976,888, U.S. Pat. No. 3,084,961 and U.S. Pat. No. 3,121,577 wherein various hose fittings are also disclosed. In the previously known fittings, it has been considered important to provide a flat nipple insertable into one end of the hose and then clamping the hose to the nipple so that the end of the hose is maintained in a substantially flat position. For this reason, the fittings included nipples formed as near as possible to a flat configuration so that the end of the hose remains substantially flat when fluid is exhausted from the hose. Nevertheless, the narrow configuration often necessitated the use of narrow elongated ports for the fluid introduction into and exhaustion from the hose interior. Such slots are restrictive to the flow of fluid and affect the inflating and deflating action of the power unit. In particular, inflation or deflation of the tube may be delayed much longer than desired in particular applications.
Another disadvantage of the previously known inflatable tube motors is that the end fittings are specially constructed to include the nipple as well as fluid couplings which permit the fitting to be connected to a fluid source. Such complex structures are difficult to design and costly to produce. Alternatively, the fluid couplings are often specially designed to fit and become clamped between the pressure plates of a fitting so that the conduit can be fixedly secured and positioned at the end of the inflatable tube motor.